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Splitting and joining are two other useful methods on strings in lists.

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So, split takes a string and turns it into a list of substrings of that string.

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So, let's suppose that we have a string, leaders and best.

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So, here we have a string leader,

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and let's suppose that we call dot split on that string.

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What dot split does,

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if we call it with nothing as an argument,

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it first looks for all the spaces in the string.

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So, here it finds a space,

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and here it finds a space,

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and it cuts the string along the spaces.

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So, what it does, is it turns this what was one string into three different strings,

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and it divides them along the spaces.

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So, the end result of this expression is going to be a list,

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where the first item is leaders,

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the second item is and,

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and the third item is best.

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One thing to note here is that split actually

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does get rid of the spaces in between all of these.

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So, this is leaders with no space afterwards and

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no space before or after and or before and after best.

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So, split essentially takes a string and splits it up into different words,

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If it's called with no arguments.

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So, let's try this out in code.

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So, suppose that we have this string,

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song equals "The Rain in Spain" and we say words equals song dot split.

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Then when we call song dot split,

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the value of this expression is going to split song along every space.

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So, we're going to get a new list that has four items, The,

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and then Rain in Spain dot dot dot.

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So, when we print out words then we should get a four item list.

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Now, we can also call dot split with an argument to specify what we want to split along.

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So, let's suppose that we actually called dot split with

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the argument e. Whatever argument we pass in here in this case e,

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specifies what we actually want to split along.

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So, here if we say we want to split along every e,

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if we split the string, leaders and best,

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then that's like crossing through every e that's in the string,

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and then the result is that we get a list where the first item is l,

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the second item is ad,

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the third item is rs and, and so on.

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So, let's try that out in code.

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So here, we have the same song.

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So, "The Rain in Spain" and let's suppose that we say song.split ("ai").

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So, when we do that,

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then we're going to search for every ai.

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So, we find this ai, then this ai.

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What we should get back is a list with three items, the,

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space, r, n, space,

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in, space, and so on.

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You see that that's exactly what we get.

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Now, the opposite of split,

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which splits a string along lines is join.

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Join takes a list of strings and joins it into one long string.

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So, split is like chopping with a knife,

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and join is like joining it back together with glue.

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So, if we say I want to use this as the glue to join the items in this list,

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what we get as the value of this overall expression is every item in this list,

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leaders and best kind of glued back together with this string.

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So, we get leaders slash and slash best.

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So, let's try that out in code.

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So here, we have a list of words,

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red, blue, and green.

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We specify a variable glue.

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This variable glue is what's going to come in-between these items when we call dot join.

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So, if we say glue.join(wds),

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and assign that to s. Then when we print out s,

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then we should expect to see red semicolon blue Semicolon green.

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So, let's test that out.

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I'm just going to comment out the rest of this code.

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So, you can see that what we got was

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the semicolon gluing back together the items and words.

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But one thing to note is that calling

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dot join doesn't effect the value of the list itself.

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So, if we print out words after having called glue.join(wds),

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then we still get out a list that has three items,

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red, blue, and green.

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Of course, we can also use a multi character string to actually join the words together.

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So, if I use three stars to join words,

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then I get red star star star,

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blue star star star green.

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I can even use an empty string to glue back the words together.

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So, if I use an empty string dot join words,

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then I get red, blue,

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green all concatenated together.

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So, let's go through some problems.

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So, this question asks us to create a variable output that's assigned to a list,

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whose elements are the words in string one.

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So, in other words, we want to split up string one into individual words.

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So, I want to assign output equal to str1.split.

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If I call that split with no arguments,

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then it splits it along the spaces.

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This question asks us to create a variable called words and assign it

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to a list whose elements are the words in the string sent,

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and it tells us not to worry about punctuation.

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So, I'm going to do something very similar here.

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I'm going to say words equals sent.split.

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Again, no arguments in dot split because we want to split it along the spaces.

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Now words is set to a list of words in a sentence.

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So, split and join are functions that

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we'll keep coming back to you throughout this course,

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and they'll end up being enormously useful.

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That's all for now, until next time.